recommendations

[serendipityfox]

Recommendations on a bathroom tiling system are welcome. it is small so would rectangles facing across or vertically enhance the space? Is a mosaic worth it? My initial choice would be a neutral beige or tan rectangles laid horizontally.
Then again I am in Thailand and can get small polished travertine tiles (15x30cm) very cheaply- the same price as ceramic, would the walls take them?
if I tile them in an offset pattern may look good, but the small size may not look pleasing. Would an opus on the walls look too busy?
I have a 2mx2m bathroom, stripped back the tiles, to sand and cement render, small glass brick window, no bath.
I have a travertine floor tile opus.
I have only reftted one bathroom before so any advice welcome.